Suppression of Unstable Flow at Small Flow Rate in a Centrifugal Blower (Simultaneous Suppression of Inducer Stall and Diffuser Stall)

Abstract

In order to suppress a periodic unstable flow occurring at small flow rates in a high specific speed type open shrouded centrifugal impeller, both effects of inlet recirculation and reduction of diffuser width on suppression of inducer stall and diffuser stall as well were analyzed by a numerical simulation and verified experimentally. The unstable flow range of the test blower was significantly improved by about 45% by adopting the optimum ring groove arrangement in addition to the narrowed diffuser width without deteriorating the blower characteristics even at the design flow rate.